GaN, a third generation wide bandgap semiconductor material, draws much attention because of its characteristics of wide bandgap, high breakdown voltage, high saturation electron velocity and the like. A silicon (Si) based lateral double-diffused metal-oxide semiconductor (LDMOS) increasingly cannot meet requirements of a base station power amplifier system for high frequency, high efficiency, large bandwidth and the like; therefore, a new generation power amplifier device fabricated by using a GaN high electron mobility transistor (HEMT) device will gradually replace the LDMOS as a dominating device in the field of base station power amplifiers.
However, the GaN HEMT device frequently generates a current collapse effect, which may cause decrease of direct drain currents, gains and radio frequency output power of the GaN HEMT device. How to reduce the current collapse effect becomes a problem that needs to be solved urgently.